Service Manual

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4.6 Fan
The control unit monitors the primary air flow to the burner by varying the fan motor power supply
voltage (DC), ensuring a correct variable speed according to the output needed.
The fan motor provides an additional control signal to enable/disable operation and the speed of
the fan is measured by the feedback signal provided by the fan’s motor. The signal consists of a
square wave with a frequency proportional to the speed of the fan.
Additionally, this system allows the appliance to detect the size of the installed vent pipes and
adapt the fan to the exhaust needs.
Figure 20 – Disassembling the Fan
Disassembly of the fan does not require removing the control unit. The steps for fan removal are:
1. Disconnect the gas sensor.
2. Disconnect the segmentation safety valves.
3. Remove the front screw.
4. Remove the fan paying attention to the fan base (the fan is trapped on the back).
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